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2012-03-08T21:16:58Z Klein, Miles V. Salamon, David Vigdor 2012-03-08T21:16:58Z 10000-01-01 1994 This thesis describes the use of large-shift ordinary Raman techniques to probe features near the charge-transfer gap in insulating cuprate materials, including the T' phase materials (R2Cu04, R=Gd, Eu, Sm, Nd, Pr), T phase La2Cu04, and 123 phase PrBa2Cu3Cu06 and YBa2Cu3Cu06+x· For all of these materials, several features are observed near 12000 cm-1 (-1.5 eV) with A2g, B1g, and A1g symmetry. At low temperatures, the largest feature with A2g symmetry splits in all the insulating cuprates into three distinct peaks: a strong main peak, and two weaker side-bands offset approximately 600 and 1500 cm-1 higher in energy respectively. A B1g feature coinciding in position with the optical conductivity peak is observed in all the T' phase materials, but not in the other insulators. An A1g peak is observed in Gd2Cu04 and Eu2Cu04 40-50 cm-1 lower in energy than the main A2g peak, and in YBa2Cu3Cu06 around 2400 cm-1 above the main A2g peak. All of these features have unusual, temperature-dependent resonance behavior with the incident photon energy, and they seem to weaken in YBa2Cu3Cu06+x as x moves through the metal-insulator transition. Some residual A2g scattering may remain in superconducting phases. We propose an explanation for many of the above observations involving a copper d xy to d x2_Y2 orbital transitions. In this picture, the main A2g peak is the d-d transition energy, the first side-band results from coupled phonon scattering, and the second sideband results from unusual coupled two-magnon scattering. Submitted by William Weathers (weathrs2@illinois.edu) on 2012-03-08T21:16:58Z No. of bitstreams: 1 1994_salamon.pdf: 6055141 bytes, checksum: f73c51dcb95bd67e6ff9dfeebeffaedc (MD5) Made available in DSpace on 2012-03-08T21:16:58Z (GMT). No. of bitstreams: 1 1994_salamon.pdf: 6055141 bytes, checksum: f73c51dcb95bd67e6ff9dfeebeffaedc (MD5) Previous issue date: 1994 Restriction data tranferred 2014-07-01T11:10:33-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: thesis Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by William Weathers (weathrs2@illinois.edu) on 2012-03-08T21:16:58Z Item is restricted indefinitely. thesis U of I Only http://hdl.handle.net/2142/29974 3779838 en ©1994 Salamon raman scattering cuprate materials Large-shift Raman scattering in insulating cuprate materials Dissertation / Thesis text Physics Physics University of Illinois at Urbana-Champaign Dissertation Ph.D.